Hollow metal shaft and manufacture of same



w. w. MCMINN 2,100,307 HOLLOW METAL SHAFT AND MANUFACTURE OF SAME.

Nov. 23, 1937.

Filed Feb. 20, 1936v ATTORNEY.

Patented Nov. 23, 193'? UNITED` STATES PATENT OFFICE l noLLow METAL SHAFT AND MANUFAC- TUBE oF SAME The present invention relates to hollow metal tubes or shafts and the manufacture of same and has particular reference to hollow metal R shafts of relatively thin wall section. 6 More specifically, the invention relates to hollow metal golf club shafts and because of its particular suitability for the making of shaftsY tively very thin wall section and consequently' light in weight. Also, in order to provide thel desired characteristics of springiness or whip in golf club shafts and the like, such shafts are advantageously tapered at least in part and it is further often desirable to vary the wall thickness longitudinally of the shaft to provide desired V strength and relativestiifness in certain portions of the shaft as compared with other portions thereof.

Heretofore, the various desired qualities and characteristics have been obtained in golf club shafts and the like by means of various diiferent modes of manufacture. but the methods hereto- .fore employed all have certain limitations with respect to the degree to which the desired characteristics of the shafts may be obtained and,

furthermore, involve relatively expensive manufacture in order to obtain such qualitiesfor physical characteristics as are obtainable within the limitations of the various methods.

In its broader aspects, my invention has for ,a 4o general object to improve upon-'methods heretofore employed in the manufacture of shaft structure of the kind under consideration and to provide asl a new article of manufacture an improved hollow metal shaft structure, particularly 46 a golf club shaft. Other and more specific obiects of the invention and the manner in which the invention may be realized, together with the advantages to be derived from its use, may best be understood from a consideration of the en- 50 suing description of the several different typical forms of shaft structure embodying the invention and illustrated by way of example in the accompanylng drawing.

In the drawing: 55 Fig. l is a perspective view illustrating part of a semi-finished shaft blank formed in accordance with certain steps of the invention;

Fig.'1a is a central longitudinal section of a semi-finished golf club shaft or shaft blank formed in accordance with certain of the steps 5v of manufacture included in the invention;

Fig. 1b is a similar section of the finished shaft;

Figs. 1c to 1h inclusive are sections taken on the respectively designated section lines of Figs. 1a and 1b; l0

Fig. 2a is a section similar to Fig. la of a different form of shaft blank embodying the invention;

Fig. 2b isa section of the nished shaft formed from the blank shown in Fig. 2a 15 Figs. 2c to 2h inclusive are sections taken on the respectively designated section lines of Figs. 2a and 2b:

Fig. 3ais a section similar to Fig. 1a of another form of blank for a shaft embodying the inven- 20 tion; t Fig. 3b is a section of the shaft formed from the blank shown in Fig. 3a.;

Figs. 3c to 3h inclusive are sections taken on the respectively designated section lines of Figs. 25 3a and 3b;

Fig. 4a is a section similar to Fig. 1a showing still another fonn of blank.for a shaft embodying the invention;

Fig. 4b is a section of the finished shaft formed 30 from the blank shown in Fig. 4a; and

Figs. 4c to 4i are sections taken on the respectively designated section lines of Figs. 4a and 4b In accordance with the invention,'the shaft 35 structure is formed from spirally wound strip material, the adjacent convolutions of which are sealed to provide an integral tubular blank structure. For reasons which will hereinafter appear, the spirally woundblank is advantageously 40 formed from strip material of uniform width and thickness and preferably provided with beveled edges.'

This strip material is first wound into spiral form, with edges abutting or overlapping, but preferably overlapping, .by any desired known method of which several are available. For instance, the strip may be spirally'- wound about a mandrel in the manner disclosed in U. S. Patent No. 2,008,423 or it may be wound by air-core winding with a machine of the kind disclosed in United States Patent No. 1,914,976. l

In Fig. 1, I have shown such a strip designatedv at Il and having beveled edges i2 and I l, wound into spiral tubular blank form with overlapping edges forming the continuous spiral seam 'indicated at lli. After the strip material is wound into the spiral blank form, designated by i8, the spiral seam it is sealed by any suitable known method, as by autogenous or other welding, brazing or the like. If brazed tubing is employed, method and article forming the claimed subject matter of my copending applications Serial Nos. 30,045, filed July 5, 1935, and Serial No. 172,053, filed October 30, 1937 as a continuation in part of Serial No. 30,045, may advantageously be availed of.

As will hereinafter more fully appear, the semi-finished spiral wound blank may be wound either to provide a cylindrical blank of uniform diameter along its length, or a tapered blank. Tapered blanks may be tapered in different Ways in order t secure the desired specific characteristics in the finished shafts, as will also be more fully described hereinafter.

The blank thus formed constitutes an integral hollow tubular member of thin wall section and of uniform wall thickness, which may be either of uniform or varying diameter along its length.

A blank of this kind is capable of being worked, in known manner, as by -swaging, hammering or even drawing, to alter its shape and to produce a finished shaft that is ordinarily, and particularly for golf shafts, tapered longitudinally, but in the, case of a shaft made from a. tapered blank, of different shape from that of the blank.

Accordingly, I produce the desired finished shaft structure by working the blank by a swaging or other suitable process to reduce the diameter of the blank along all or a portion of its length and to thereby increase the wall thickness of the portion or portions where the diameter of the blank is reduced.

Depending upon the shape of the spirally wound blank with respect to successive diameters from end to end thereof, as compared with the successive diameters of the nished shaft, I :am enabled to control the amount of thickening of the metal of the wall at any desired place along the length of the shaft, while at the same time producing a shaft structure having uniform outer diameter or uniform or suitably varied tapered outersurface presenting acceptable outward appearance.

The manner in which this is obtained is conveniently illustrated in the various sectional views of the drawing.

Considering flrst Fig. 1a, the blank 20 is of uniform diameter from end to end and of uniform wall thickness from end to end, as indicated in this figure and Figs. 1c, 1d and 1e. From the blank 20, a finished golf club shaft 22, which in this instance is shown as having uniformly diminishing taper from the handle end 24 to the c lub head end 26, is formed by suitable working operations and, as a result of this tapering operation, the wall thickness of the material is increased toward the latter end of the shaft as indicated in exaggerated fashion in the drawing. For a golf club shaft of normal proportions, the diameter of the handle end will be of the order of 1/2 to inch and at the club head end the diameter will be of the order of 1A to inch. Normally, for such a shaft, the thickness ofthe blank strip material from 'which the blank is formed will be of the order of .O15-to .025 inch, which thickness will be substantially retained at the handle end and which will, assuming a blank of cylindrical form as shown in Fig. 1a, be increased in thickness by approximately .004 inch to .007 inch at the club head end of the nmhed shaft.

A finished golf club shaft of uniformly tapered diameter and having uniformly increasing wall thickness' from the handle end to the head end will have certain well known and predictable characteristics of flexibility and whip. 'llhese characteristics are not 'suitable for all users and in order to provide shafts having diierent characteristics in order to meet different specications of flexibility and whip, all that is required, when my invention is employed, is to vary the winding of the strip material to form a blank of other than straight cylindrical form, assuming that the final form of the shaft is to be of the usual characteristic diminishing taper from handle end to head end. In some instances, it is desirable to provide a comparatively heavy walled and sti shaft portion adjacent to the club head end, both from the standpoint of the whip characteristics of the shaft and also from the standpoint of providing ample wall thickness at the place of attachment between the shaft and the club head. In order to secure this result, a blank may be, in accordance with the invention, wound to the form shown infFig. 2a wherein the strip material is wound to uniform diameter from the handle end 24 to the point 28. From the point 28 to the club head end 26, the strip is wound with increasing diameter toward the latter end to provide additional metal per unit length of the blank at this end portion. The blank thus formed is then, as shown in Fig. 2b, worked to the desired final taper and because of the relation of the diameters in the blank and in the nished shaft at corresponding places along the length of the blank and shaft, the wall thickness increases at one rate from the handle end to the point 28 and from this point to the club head end, it continues to Aincrease but at a greater rate. The difference in the characteristics of the two shafts will be evident by comparison of Figs. 1b, 1f, 1g and 1h with the correspondingly lettered figures of the present modification.

In Fig. 3a, a blank is shown in which the handle portion of the shaft is wound with increasing taper from the handle end to about the mid point of the shaft, and from this point to the club head end the blank is wound with diminishing taper toward the latter end. Thereafter, upon working of the blank to the tapered finished shaft form shown in Fig. 3b, a. shaft is produced in which the thickness of the wall structure increases fromlthe handle end to the mid portion, and from the mid portion to the club head end the thickness decreases toward the latter end, the extent of such decrease in thickness depending upon the relation of the taper in this portion of the blank to the taper in the corresponding portion of the finished shaft.

In Fig. 4a, a blank is illustrated which is of di minishing taper from the handle end to the point 30, and from this point of increasing diameter to the club head end. This form of blank produces a finished uniformly tapered shaft having wall thickness the character of which is illustrated in Fig. 4b, that is, with substantially uniform wall thickness between the handle end 2l and the point 30, and with comparatively rapidly increasing wall thickness from this point to the head end 26.

From the foregoing examples, it will be evident that the principles of the invention may be applied in a wide variety of specific ways in order to secure almost any desired variations, along the Iength of a finished shaft, of the wall thickness thereof and that the desired variations in thickness of the wall structure may be 'obtained with different external shaft contours, simply by properly relating the diameters of the blank at various places along its length to the desired nal diameters'of the finished shaft at corresponding places along its length.

In order to illustrate in as" simple a manner as possible the nature of the results obtainable with the invention, the various modifications hereinbefore described have all been shown as shafts which in the finished form are uniformly tapered externally from the handle end to the club head end and the portions of the several nished shafts shown in the drawing have been shown as of the same length as the blanks from which they are formed. It will be evident, however, that the final external form of shaft may be different from the form illustrated and also that as a result of the operations performed on the blank to work it into a finished tapered form, the length after working may be greater 'than that of the original blank.

In the manufacture of golf club shafts, the handle end portions of the shafts may advantageously be wound in numerous instances to cylindrical form in the blank and left in this form, the tapering operations being conned to those portions of the shaft that are exposed in the finished product.

It will further be apparent that the method hereinbefore described is extremely simple and practical in its nature and results in the production of new shaft products' having highly desirable characteristics not possessed by shafts heretofore produced for like uses. By the use of this invention, shaft structures having different wall thicknesses along their length may be produced from very cheap and easily procured strip material of uniform width and thickness, by means of simple winding and forming operations that are relatively very inexpensive as compared with processes heretofore employed, and that have required the use of seamless tubular blanks produced onlyV at relatively very much greater expense, or by longitudinally seamed blanks not having characteristics of physical strength, particularly with respect to resistance in torsion, that are possessed by the spirally wound structures of the present invention.

vFurthermore, it will be evident that by applying the principles of the present invention, it is possible to produce shaft structures having variations in wall thickness along their lengths, the-'specific characteristics of which variations are unobtainablev as a practical manufacturing proposition by methodsn of manufacture heretofore proposed.

While in compliance with the requirements of the patent statutes, I have illustrated the application of the invention to different modifications of structure, it is to be understood that such modifications are shown and have been described herein only by way of example and that the invention embraces all that is included within the scope of the appended claims when they are construed as broadly as is consistent with the state of the prior art.

I claim:

1. The method of making a hollow metal shaft structure which consists in winding a strip of metal of substantially uniform width and thickness into a series of contiguous spiral convolutions having a continuous spiral seam therebetween, sealing said seam to produce an integral tubular spiral wound blank and thereafter reducing the diameter of said blank along certain portions thereof to provide a finished shaft structure having different wall thicknesses at different places longitudinally of its length.

2. The method of making a hollow metal shaft structure which consists in winding a strip of metal of substantially uniform width and thickness into a series of contiguous spiral convolutions of uniform diameter and having a continuous spiral seam therebetween, sealing said seam to produce a cylindrical integral tubular spiral wound blank and thereafter working said blank to produce a finished hollow tubular shaft having an outer surface tapered longitudinally of at least a portion of the length of the shaft and having wall structure increasing in thickness in the direction of diminishing taper.

3. The method of making an integral hollow tubular metal shaft which consists in winding a strip of metal of substantially uniform width and thickness into a series of contiguous spiral convolutions of different diameters and having a continuous spiral seam therebetween, sealing said seam to form an integral hollow tapered .tubular blank having uniform wall thickness and thereafter working said blank to decrease the external diameters of desired portions of the blank to produce a finished hollow tubular shaft structure of different external configuration than that'of the blank and having Wall structure of different thickness at dierent places along the length of the shaft.

4. As a new article of manufacture, a hollow tubular metal shaft formed from a strip of metal of substantially uniform width and thickness wound into a series of contiguous spiral convolutions and having a sealed continuous spiral seam between adjacent convolutions, different ones of said convolutions along the length of the shaft having different wall thickness.

5. In a golf club, a hollow tubular metal shaft formed from a strip of metal of substantially uniform width and thickness wound into a series of contiguous spiral convolutions, certain of said convolutions being of different diameters to provide a tapered shaft portion and different ones of said convolutions in said tapered portion of the shaft having different wall thicknesses, there being a sealed continuous spiral seam between adjacent convolutions.

6. In a golf club, a tapered hollow tubular metal shaft comprising a series of spirally wound contiguous convolutions and having a sealed continuous spiral seam between adjacent convolutions, the wall thickness of the shaft increasing in the direction from the handle portion of the shaft to the club head portion of the shaft and the rate of increase in wall thickness per unit length of the shaft being greater in the club head portion of the shaft than in the remaining portion of the shaft.

'7. In a golf club, a hollow tubular metal shaft comprising a series of contiguous spirally wound convolutions and having a sealed continuous spiral seam between adjacent convolutions, said shaft having increasing wall thickness from the handle end portion thereof to a place between the mid portion of the shaft and the club head end of the shaft and having wall thicknefs increasing at greater rate toward said club head end in the portion of the shaft between said place and said head end.

8. In a golf club, a hollow tubular metal shaft having wall thickness increasing toward the club head end of the shaft in the portion of the shaft between said place and said club head end.

9. In a golf club, a hollow tubular metal shaft comprising a series of contiguous spirally wound convolutions and having a sealed continuous spiral seam between adjacent convolutions, said the handle end of the shaft and the place of at-l tachment of the club head to the shaft.

10. The method of making an integral hollow tubular metal shaft which consists in winding a strip of metal of substantially uniform width and thickness into a series of contiguous spiral convolutions having a continuous spiral seam therebetween and forming a shaft blank having a different relation of successive diameters than desired in the finished shaft longitudinally of at least a portion of the blank, sealing said seam to join said convolutions, whereby to produce an integral blank and thereafter Working said blank to alter the relationship of said successive diameters by decreasing a plurality of such diameters to thereby form a shaft of different external configuration than that of the blank and having increased wall thickness along at least a.

portion thereof.

l1. The method of making an integral hollow tubularymetal shaft which consists in winding a strip of metal of substantially uniform width and thickness into a series of contiguous spiral convolutions having a continuous spiral seam therebetween, to form a substantially straight shaft blank having a relation of successive diameters longitudinally of at least a portion of the blank other than that desired in the finished shaft, sealing said seam to provide an integral blank for subsequent'working and thereafter Working said blank to desired external configuration by reducing certain of said diameters to thereby produce a. shaft of desired external configuration having at least a portion in which the wall thickness varies longitudinally of the shaft due to such Working.

- WILEY W. McMINN. 

